ИСТИНА

Introduction: Creatine/creatinephosphate (Cr/PCr) plays the key role in cellular energy methabolism and, in particular, in cells, which have high energy requirements, such as neurons (Andres et al., 2008). However, its implications for human memory are somewhat controversial. Recent studies show, that hippocampal NAA/Cr levels are lowered in patients with Alzheimer's disease and in people with mild memory impairment (Caserta et al., 2008). In present study we compared Cr/PCr levels in hippocampi with memory characteristics in elderly people without any cognitive impairment. Methods: We compared Cr/PCr level (3.03 ppm) in hippocampi of both hemispheres and, as a control measurment, in right inferior parietal cortex and subventricular zone with neuropsychological verbal and visuospatial memory characteristics of 18 females (mean age – 58.2 years old). For each subject we performed 3T proton magnetic resonance spectroscopy. Verbal and visuospatial memory capacity, permanency and the amount of different memory errors were assessed with Luria's neuropsychological tests. We calculated non-parametric correlations (p<0.05) between individual neuropsychological and biochemical measurements. Results: Verbal memory capacity (r=0.50) and permanency (r=0.63, p<0.01), as well as visuo-spatial memory capacity (r=0.66, p<0.01) and permanency (r=0.48) correlate positively with Cr/PCr level in left hippocampus. On the other hand, the amount of different visuo-spatial memory errors correlates negatively with Cr/PCr level in left hippocampus (r=-0.60, p<0.01 for the amount of confabulations, r=-0.53 for the amount of stimuli groups contaminations, r=-0.49 for the amount of sequence errors). No significant correlations between Cr/PCr levels in right inferior parietal cortex and subventricular zone and memory characteristics were revealed. Conclusions: According to the obtained data, high Cr/PCr level in left hippocampus correlates with high memory capacity and permanency for both verbal and visuo-spatial memory and is also related to the decline in the amount of different memory errors. This findings correspond well with the results of Souza et al. (2012) study, which showed that creatine injection leads to spatial memory improvement in rats due to an increase in pCREB and pCaMKII levels. Our results can also explain the findings of McMorris et al. (2007), according to which cognitive processes performance, e.g. memory, in elderly people was improved after creatine supplementation. Thus, it can be hypothesized, that Cr/PCr level in hippocampus is related not only to the ATP synthesis/degradation, but can affect the synthesis of cAMP, the secondary messenger, which is necessary for memory consolidation (Kandel, 2007).